The present invention relates to valves and more particularly, to improved gate valves.
The present invention is particularly suitable for gate valves which are of a relatively large size ranging, for example, from 8 inches through 36 inches. The valve of the invention is suitable as a gate valve for cyclic temperature service such as for use in cyclic powerformers, although the gate valve of the invention is suitable for most process plant services. While the valve of the invention can be used for all sizes and pressure ratings, it is particularly designed for sizes on the order of the above range and for pressure ratings of 150 pounds through 600 pounds.
Conventional valves of the above general type are made of castings which have proved from experience to be unsuited for relatively great and frequent temperature fluctuations.
Thus, with conventional valves of this type the castings have been known to crack in some cases in as short a time as within one year after a valve is put into service. Such cracking creates considerable problems either in connection with repair of the cracks or in connection with replacement of cracked components.